Obama's victories in Wisconsin and Hawaii on Tuesday his ninth and 10th in a row left him with 1,178 pledged delegates won in primaries and caucuses in The Associated Press' count. Clinton has 1,024.

Another 1,025 remain to be awarded, most of them in contests in 14 states, Guam and Puerto Rico.

Further complicating Clinton's challenge, Obama appears particularly well-positioned to win at least one of the remaining states with ease. Mississippi, with a primary on March 11, fits a pattern of Southern states with large black populations that he has won handily, including South Carolina, Alabama, Georgia and Louisiana.

The rival campaigns maintain their own delegate counts. And while both agree Obama is the leader, they differ on the significance.